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1.
Sampling from partially rank-ordered sets 总被引:1,自引:0,他引:1
Omer Ozturk 《Environmental and Ecological Statistics》2011,18(4):757-779
In this paper we introduce a new sampling design. The proposed design is similar to a ranked set sampling (RSS) design with
a clear difference that rankers are allowed to declare any two or more units are tied in ranks whenever the units can not
be ranked with high confidence. These units are replaced in judgment subsets. The fully measured units are then selected from
these partially ordered judgment subsets. Based on this sampling scheme, we develop unbiased estimators for the population
mean and variance. We show that the proposed sampling procedure has some advantages over standard ranked set sampling. 相似文献
2.
Nonparametric mean estimation using partially ordered sets 总被引:2,自引:0,他引:2
Jesse Frey 《Environmental and Ecological Statistics》2012,19(3):309-326
In ranked-set sampling (RSS), the ranker must give a complete ranking of the units in each set. In this paper, we consider a modification of RSS that allows the ranker to declare ties. Our sampling method is simply to break the ties at random so that we obtain a standard ranked-set sample, but also to record the tie structure for use in estimation. We propose several different nonparametric mean estimators that incorporate the tie information, and we show that the best of these estimators is substantially more efficient than estimators that ignore the ties. As part of our comparison of estimators, we develop new results about models for ties in rankings. We also show that there are settings where, to achieve more efficient estimation, ties should be declared not just when the ranker is actually unsure about how units rank, but also when the ranker is sure about the ranking, but believes that the units are close. 相似文献
3.
Fresh water, a fundamental element of all estuarine ecosystems, is South Africa’s most limited natural resource. Recent projections
indicate that by the year 2020 the country will be utilizing all its exploitable freshwater sources. Steeply increasing demands
by a rapidly growing population on this limited commodity have already resulted in a severe reduction of water supplies to
natural users such as estuaries — this trend is predicted to increase in the future. Concurrent with excessive water abstraction,
poor land husbandry (e.g. soil erosion) in many catchment basins and pollution (e.g. salinization) in return flows have led
to a serious deterioration in water quality. In contrast, a review of estuarine responses to varying flow regimes stresses
the strong dependence of local systems on riverine fresh water inputs of adequate quantity and quality. Freshwater dependence
is i.a. expressed in: flooding events that scour accumulated sediments, riverine nutrient input to drive estuarine phyto-
and zooplankton production, axial salinity gradients that increase habitat and species diversity, and maintenance of open
tidal inlets that prevent salinity and temperature extremes and facilitate larval exchange, fish migrations and tidal flushing
of salt marshes. Thus, estuarine conservation will have to encompass management of rivers and watersheds and play an increasingly
political role in decision processes concerning water allocations among ‘human’ and ‘natural’ users. 相似文献
4.
Fresh water, a fundamental element of all estuarine ecosystems, is South Africa’s most limited natural resource. Recent projections
indicate that by the year 2020 the country will be utilizing all its exploitable freshwater sources. Steeply increasing demands
by a rapidly growing population on this limited commodity have already resulted in a severe reduction of water supplies to
natural users such as estuaries-this trend is predicted to increase in the future. Concurrent with excesive water abstraction,
poor land husbandry (e.g. soil erosion) in many catchment basins and pollution (e.g. salinization) in return flows have led
to a serious deterioration in water quality. In contrast, a review of estuarine responses to varying flow regimes stresses
the strong dependence of local systems on riverine fresh water inputs of adequate quantity and quality. Freshwater dependence
is i.a. expressed in: flooding events that scour accumulated sediments, riverine nutrient input to drive estuarine phyto-
and zooplankton production, axial salinity gradients that increase habitat and species diversity, and maintenance of open
tidal inlets that prevent salinity and temperature extremes and facilitate larval exchange, fish migrations and tidal flushing
of salt marshes. Thus, estuarine conservation will have to encompass management of rivers and watersheds and play an increasingly
political role in decision processes concerning water allocations among ‘human’ and ‘natural’ users. 相似文献
5.
This study examines the impact of flooding on land of high conservation value located along part of the southern shoreline
of the River Clyde Estuary in western Scotland. This paper hypothesizes that, over the next 50 years, the frequency and extent
of coastal flooding will increase due to the gradual effect of global warming and the consequent rise in sea-level and increase
in storminess. It is argued that because of the great cost of constructing new flood defence systems it will not be possible
to protect all land areas to an equal extent from flooding. A means of ranking different land use will be necessary so that
society can make a rational judgement concerning which sections of coastline will be worth protecting. This study provides
a methodology that combines an objective ranking of conservation areas using non-economic indicators with a GIS model of flood
potential, and permits accurate forecasts of flood losses to conservation areas of different ecological value. The conservation
case study used in this paper proposes the use of an ecological weighting value based on five ecological variables each of
10 categories. Tables and maps identify the sites that have been highlighted as consisting of the most ‘valuable’ conservation
sites. The methodology makes extensive use of geographical information systems (GIS) to model the predicted areas of flooding
and to calculate conservation weighting values of the land areas. 相似文献
6.
This study examines the impact of flooding on land of high conservation value located along part of the southern shoreline
of the River Clyde Estuary in western Scotland. This paper hypothesizes that, over the next 50 years, the frequency and extent
of coastal flooding will increase due to the gradual effect of global warming and the consequent rise in sea-level and increase
in storminess. It is argued that because of the great cost of constructing new flood defence systems it will not be possible
to protect all land areas to an equal extent from flooding. A means of ranking different land use will be necessary so that
society can make a rational judgement concerning which sections of coastline will be worth protecting. This study provides
a methodology that combines an objective ranking of conservation areas using non-economic indicators with a GIS model of flood
potential, and permits accurate forecasts of flood losses to conservation areas of different ecological value. The conservation
case study used in this paper proposes the use of an ecological weighting value based on five ecological variables each of
10 categories. Tables and maps identify the sites that have been highlighted as consisting of the most ‘valuable’ conservation
sites. The methodology makes extensive use of geographical information systems (GIS) to model the predicted areas of flooding
and to calculate conservation weighting values of the land areas. 相似文献
7.
A swarm of honeybees provides a striking example of an animal group performing a synchronized departure for a new location;
in this case, thousands of bees taking off at once to fly to a new home. However, the means by which this is achieved remain
unclear. Shortly before takeoff, one hears a crescendo of a high-pitched mechanical signal—worker piping—so we explored the
role of this signal in coordinating a swarm’s mass takeoff. Specifically, we examined whether exclusively nest site scouts
produce the worker piping signal or whether it is produced in a relay or chain reaction fashion. We found no evidence that
bees other than the scouts that have visited the swarm’s chosen nest site produce piping signals. This absence of relay communication
in piping suggests that it is a signal that only primes swarms for takeoff and that the release of takeoff is triggered by
some other signal or cue; perhaps the takeoff of bees on the swarm periphery as they reach flight temperature in response
to piping. 相似文献
8.
Gábor Herczeg Abigél Gonda Jarmo Saarikivi Juha Merilä 《Behavioral ecology and sociobiology》2006,60(3):405-414
According to Huey and Slatkin’s [Q Rev Biol 51:363–384, 1976] cost–benefit model of behavioural thermoregulation, lizards should adjust their thermoregulatory strategy between active thermoregulation and thermoconformity (no thermoregulation) according to the costs (time and energy spent thermoregulating, exposure to predators), benefits (optimised physiological performance) and thermal quality of environment associated with a given situation. However, Gilchrist’s [Am Nat 146:252–270, 1995] model of thermal specialisation suggests that apparently costly mechanisms of behavioural thermoregulation can greatly increase fitness if the optimal body temperature is achieved. Field studies of ectotherm thermoregulatory strategies under extreme cold conditions and experiments testing the effects of cool environments on thermoregulatory behaviour are surprisingly scarce. We conducted laboratory experiments to test if common lizards Zootoca
vivipara (an active thermoregulator in the field) are able to switch between active thermoregulation and thermoconformity in response to different thermal environments. We found that lizards in treatments with an opportunity to reach their preferred body temperature thermoregulated accurately, maintained their level of daily activity and improved their body condition considerably. In contrast, lizards in the treatment where the preferred body temperature could not be reached became thermoconformers, decreased their daily activity (except for gravid females) and did not increase their body condition. Our results show that lizards can indeed change their thermoregulatory strategy but stress that maintaining the preferred body temperature and, thus, optimising the physiological performance have high priority in lizard behaviour. 相似文献
9.
The complexity of the present data-centric world finds its expression in the increasing number of multi-indicator systems.
This has led to the development of multicriteria ranking systems based on partial orders. Order theory is a main pillar of
structural mathematics. Partial orders help to reveal why an object of interest holds a certain ranking position and how much
it is subject to change if a composite indicator is upgraded. Order theory helps to derive linear or weak orders without indicator
weighting schemes. Hence, rankings obtained from decision support systems (DSS) which depend on many parameters beyond the
data matrix can be checked and discrepancies can lead to examine the parameters of the DSS. Order theory helps discover association
and implication structures derived from formal concept lattices. Association and implication networks among the attributes
of the data matrix allow more insights into multi-indicator systems and lead to new hypotheses and motivate further research.
Some new and innovative concepts, like separated subsets, antagonistic indicators, ranking stability fields are rendered.
Separated subsets are the typical outcome of a partial order analysis; their identification leads to antagonistic indicators,
which are responsible for the separatedness of object’s subsets. Numerical aggregation can be performed step-by-step and the
question which values of a weight lead to an order inversion is of high interest. The concept of stability fields is one possible
answer, discussed in this paper. After an outline of partial order theory some more specific theoretical results are shown,
then we discuss the role of composite indicators in the light of partial order and give some examples of interesting applications
of partial order. Finally examples are selected from real life case studies of watersheds, environmental performance evaluations,
child well being, geographic and administrative regions and more. 相似文献
10.
Liza R. Moscovice Marlies Heesen Anthony Di Fiore Robert M. Seyfarth Dorothy L. Cheney 《Behavioral ecology and sociobiology》2009,63(10):1471-1482
Adult male chacma baboons (Papio hamadryas ursinus) form preferential associations, or friendships, with particular lactating females. Males exhibit high levels of affiliative
contact with their friends’ infants and defend them from potentially infanticidal attacks (Palombit et al. 1997). Little is known about males’ associations with juveniles once they have passed the period of infanticidal risk. We conducted
an observational, experimental, and genetic study of adult male and juvenile chacma baboons in the Moremi Reserve, Botswana.
We identified preferential associations between males and juveniles and used behavioral data and a playback experiment to
explore whether those associations have potential fitness benefits for juveniles. We determined whether males preferentially
invest in care of their own offspring. We also determined how often males invest in care of their former friends’ offspring.
The majority of juveniles exhibited preferential associations with one or two males, who had almost always been their mother’s
friend during infancy. However, in only a subset of these relationships was the male the actual father, in part because many
fathers died or disappeared before their offspring were weaned. Male caretakers intervened on behalf of their juvenile associates
in social conflicts more often than they intervened on behalf of unconnected juveniles, and they did not appear to differentiate
between genetic offspring and unrelated associates. Playbacks of juveniles’ distress calls elicited a stronger response from
their caretakers than from control males. Chacma males may provide care to unrelated offspring of former friends because the
costs associated with such care are low compared with the potentially high fitness costs of refusing aid to a juvenile who
is a possible offspring. 相似文献
11.
A common explanation for hunting in groups is that doing so yields a greater per capita caloric benefit than hunting solitarily.
This is logical for social carnivores, which rely exclusively on meat for energy, but arguably not for omnivores, which obtain
calories from either plant or animal matter. The common chimpanzee, Pan troglodytes, is one of the few true omnivores that regularly hunts in groups. Studies to date have yielded conflicting data regarding
the payoffs of group hunting in chimpanzees. Here, we interpret chimpanzee hunting patterns using a new approach. In contrast
to the classical assumption that hunting with others maximizes per capita caloric intake, we propose that group hunting is
favored because it maximizes an individual’s likelihood of obtaining important micronutrients that may be found in small quantities
of meat. We describe a mathematical model demonstrating that group hunting may evolve when individuals can obtain micronutrients
more frequently by hunting in groups than by hunting solitarily, provided that group size is below a certain threshold. Twenty
five years of data from Gombe National Park, Tanzania are consistent with this prediction. We propose that our ‘meat-scrap’
hypothesis is a unifying approach that may explain group hunting by chimpanzees and other social omnivores. 相似文献
12.
José S. Antunes do Carmo Mechteld ten Voorde Maria G. Neves 《Journal of Coastal Conservation》2011,15(4):531-546
Surfing has becoming more and more attractive in the past few decades, constituting nowadays an important source of revenue
for many countries with extensive coastlines. For this purpose and also for environmental reasons, the conventional ways of
protecting a coastline appear to entail some disadvantages. An innovative and interesting way of improving surfing capacities
and contributing to protect a local coastal zone is by means of multifunctional artificial reefs. A multifunctional artificial
reef (MFAR) is a submerged structure that serves several purposes; in particular, it may enhance the surfing possibilities
and the environmental value of the local area. This structure has some promising new aspects, too: first, it provides an unimpaired
visual amenity; second, it offers tourist and economic benefits by improving the surfing conditions; third, it can enhance
the environmental value of the area where it is built, and fourth, if designed properly, the down drift erosion can be minimal.
An appropriate reef design in terms of ‘surfability’, i.e. the possibility to surf a wave, for the Leirosa beach, located
to the south of Figueira da Foz, midway along Portugal’s West Atlantic coast, has been investigated. In order to achieve the
best design several steps were conducted. First, the performance of the Boussinesq-type COULWAVE model is tested with experimental
data. Next, this numerical model is used to define the best values for three design parameters: reef angle; geometry of the
reef (without or with a platform), and horizontal dimensions for the appropriate geometry. A preliminary design was achieved
step by step, making use of the theory and of the state of the art of multifunctional reefs. This reef geometry is used in
the numerical study. In terms of ‘surfability’ and for the conditions of the local coastline of Leirosa, the following values
were found for the main parameters: a reef angle of 66°; a structure height of 3.20 m; a reef geometry composed of a delta
without a platform; a reef submergence of 1.50 m, and a structure seaward slope of 1:10. 相似文献
13.
Different ranking methods: potentialities and pitfalls for the case of European opinion poll 总被引:1,自引:0,他引:1
Paola Annoni 《Environmental and Ecological Statistics》2007,14(4):453-471
Prioritization and ranking of objects are primary needs in various substantive fields. It might be said that ranking and comparison
are the first step in every risk assessment procedure, whatever the ‘risk’ is intended as: social, environmental, political
or economic. Often objects to be ranked are valued by a multi-dimensional attribute which is usually transformed into a composite
numerical score. In spite of conventional solutions, the author agrees with recent recommendations of performing multiple
ranking, keeping indicators separated. Different innovative methods are analyzed and compared: Hasse diagrams method, POSAC
and Nonlinear PCA. The first one stems directly from partial order theory, the second one may be seen as an approximation
of Hasse representation in a two dimensional space, whilst the third one belongs to the wide set of non-linear multivariate
techniques and it is particularly suitable in handling data of categorical type. Among them, the first two methods compare
objects on the basis only on order property of data, whilst the last one simultaneously performs an optimal scale of qualitative
attributes and a ranking of objects. The case study is based on the Eurobarometer survey carried out in 2002, at the request
of the European Commission, which collects Europeans opinion about various political and social issues. The analysis is focused
on users’ level of satisfaction about access easiness, cost, quality, information received and contracts of various services
of general interest, such as telephone services, power (gas and electricity) providers, water and postal utilities, urban
and rail transports. Separate indicators are set up for each facet of each service within different European regions. Eventually,
the ranking of European regions is performed on the basis of the overall performance of services of general interest, as perceived
by users. Selected methods lead to almost alike results, still with some differentiations due to different approaches used.
As it frequently occurs, each method has its own advantages and pitfalls which are here explored and compared. 相似文献
14.
Heterospecific matings are generally assumed to be unconditionally disadvantageous due to reduced viability or fertility of
hybrid offspring. For female collared flycatchers (Ficedula albicollis) mated to male pied flycatchers (Ficedula hypoleuca), the cost of heterospecific pair formation is reduced due to high levels of conspecific extra-pair paternity and a male-biased
offspring sex ratio. In order to investigate whether these cost-reducing mechanisms are the result of female mating strategies,
rather than being a by-product of species incompatibilities, we manipulated the plumage of male collared flycatchers before
pair formation to make them resemble male pied flycatchers. Since species incompatibilities are absent in this design, any
systematic effect of manipulation on sex ratio or paternity would indicate a role of female mating strategy. Paternity was
determined by means of a likelihood approach that controls the errors made in assigning a chick to be ‘within-pair’ or ‘extra-pair’.
Neither the sex ratio nor the male share of paternity was affected by the manipulation in a systematic manner. We therefore
conclude that our experimental data provide no support for the suggestion that female behavioural strategies are markedly
adjusted in response to formation of mixed-species pairs.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
This paper develops statistical inference for population mean and total using stratified judgment post-stratified (SJPS) samples. The SJPS design selects a judgment post-stratified sample from each stratum. Hence, in addition to stratum structure, it induces additional ranking structure within stratum samples. SJPS is constructed from a finite population using either a with or without replacement sampling design. Inference is constructed under both randomization theory and a super population model. In both approaches, the paper shows that the estimators of population mean and total are unbiased. The paper also constructs unbiased estimators for the variance (mean square prediction error) of the sample mean (predictor of population mean), and develops confidence and prediction intervals for the population mean. The empirical evidence shows that the proposed estimators perform better than their competitors in the literature. 相似文献
16.
Francesca Gherardi 《Behavioral ecology and sociobiology》2006,59(4):500-510
A study was conducted to determine whether asymmetries in both resource-holding potential (RHP) and resource value (RV) influence
dominance and fighting behavior in the hermit crab Pagurus longicarpus. A total of 120 groups of three crabs were observed for 10 min in four experiments that tested all diverse combinations of
equal/different RHP (i.e. ‘body size’) and equal/different RV (i.e. ‘shell size’ and ‘shell quality’). In a fifth experiment,
dominant and subordinate individuals of the same size category (26 groups) were forced to enter shells of opposite quality
than those previously occupied, and then the behavior of the reconstituted original groups was observed for additional 10 min.
As expected, crabs in lower quality shells were more willing to initiate and to escalate fights. However, their attacks were
directed to any crab of the group, independently of the defender's shell quality, and the fight duration did not vary with
the different value of the resources at stake. This may indicate that P. longicarpus is unable to assess the quality of the shells available in its social environment but bases its tactical decisions during
fights solely on its own resource. This suggestion was confirmed by the change in the fighting behavior of crabs whose shell
quality was experimentally altered. This manipulation induced an overall increase in the intensity of aggression, drastic
modification of crab behavior, and inversion of the hierarchy even though these crabs have had previous experiences of wins/losses
and were familiar to the other members of the group. In this species, large crab size and/or the occupancy of adequate (and
oversized) shells appeared to be the most likely determinant of contest resolution. Individuals seemed to retain a memory
of the previously held resource and behaved accordingly. 相似文献
17.
We investigated the effects of population fluctuation on the offspring’s sex allocation by a weakly polygynous mouse, Apodemus argenteus, for 3 years. In acorn-poor seasons, heavier mothers invested more in sons, and lighter mothers invested more in daughters.
In acorn-rich seasons, heavier mothers invested more in daughters, and lighter mothers invested more in sons. Maternal body
condition and litter size affected the sex allocation. Furthermore, there was a maternal investment trade-off between a son’s
birth mass and the number of daughters. Based upon the effect of population fluctuation on the lifetime reproductive success
of each sex, we proposed the new “safe bet hypothesis”. This hypothesis predicts that frequent and unpredictable change in
female distribution, which is often caused by abrupt fall in food condition, favors female-biased maternal investment to offspring
by polygynous mammals and is applicable to many small mammals inhabiting in unstable environments. 相似文献
18.
Conservation threats and the phylogenetic utility of IUCN Red List rankings in Incilius toads
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Phylogenetic analysis of extinction threat is an emerging tool in the field of conservation. However, there are problems with the methods and data as commonly used. Phylogenetic sampling usually extends to the level of family or genus, but International Union for Conservation of Nature (IUCN) rankings are available only for individual species, and, although different species within a taxonomic group may have the same IUCN rank, the species may have been ranked as such for different reasons. Therefore, IUCN rank may not reflect evolutionary history and thus may not be appropriate for use in a phylogenetic context. To be used appropriately, threat‐risk data should reflect the cause of extinction threat rather than the IUCN threat ranking. In a case study of the toad genus Incilius, with phylogenetic sampling at the species level (so that the resolution of the phylogeny matches character data from the IUCN Red List), we analyzed causes of decline and IUCN threat rankings by calculating metrics of phylogenetic signal (such as Fritz and Purvis’ D). We also analyzed the extent to which cause of decline and threat ranking overlap by calculating phylogenetic correlation between these 2 types of character data. Incilius species varied greatly in both threat ranking and cause of decline; this variability would be lost at a coarser taxonomic resolution. We found far more phylogenetic signal, likely correlated with evolutionary history, for causes of decline than for IUCN threat ranking. Individual causes of decline and IUCN threat rankings were largely uncorrelated on the phylogeny. Our results demonstrate the importance of character selection and taxonomic resolution when extinction threat is analyzed in a phylogenetic context. 相似文献
19.
Monica Gagliano Mark I. McCormick James A. Moore Martial Depczynski 《Marine Biology》2010,157(8):1849-1856
Ocean acidification is one of the key threats facing coral reef ecosystems, but there are few estimates of spatial and temporal
variability in pH among reef habitats. The present study documents levels of spatial variability in pH among coral reef habitats
(9 to 10), among locations separated by 100’s km of latitude and between east (Great Barrier Reef, GBR) and west (Ningaloo
Reef) coasts of Australia. Differences were found in pH between inshore and offshore waters along Ningaloo Reef (means 8.45,
8.53, respectively). Replicate assessments here ranged from 8.22 to 8.64. On the GBR, the range of values over all habitats
and replicates was 0.39 pH units (7.98 to 8.37). There were minor but significant differences of 0.05 pH units between 5 consecutive
days for habitats on average. Highest pH was recorded in filamentous algal beds maintained by the damselfish Dischistodus perspicillatus. Lowest pH was found in water extracted from sand-dwelling goby holes. While there were marked changes in pH over a 48-h
sampling period among 4 habitats at Lizard Island (GBR), there was little evidence of a diel trend. Understanding how pH varies
at scales that are relevant to organisms that live on shallow coral reefs is crucial for the design and interpretation of
experiments that test the effects on organisms of the changes in water chemistry predicted to affect oceans in the future. 相似文献
20.
Combining ranking information in judgment post stratified and ranked set sampling designs 总被引:1,自引:0,他引:1
Omer Ozturk 《Environmental and Ecological Statistics》2012,19(1):73-93
Judgment post stratified (JPS) and ranked set sampling (RSS) designs rely on the ability of a ranker to assign ranks to potential
observations on available experimental units. In many settings, there are often more than one rankers available and each of
these rankers provide judgment ranks. This paper proposes two sampling schemes, one for JPS and the other for RSS, to combine
the judgment ranks of these rankers to produce a strength of agreement measure for each fully measured unit. This strength
measure is used to draw inference for the population mean and cumulative distribution function. The paper shows that the estimators
constructed based on this strength measure provide a substantial improvement over the same estimators based on judgment ranking
information of a single best ranker. 相似文献